The present invention relates to a tobacco filter. More particularly, the present invention is directed to a tobacco smoke filter that is selective in the removal of various constituents, for example, hydrogen cyanide, phenols, and various amines from the smoke stream.
A wide variety of materials have been suggested in the prior art as filters for tobacco smoke. Thus, such products as cotton, paper, asbestos, regenerated cellulose, and certain synthetic fibers have been disclosed as filter media for tars and nicotine of cigarettes, pipe and cigar smoke.
Although the above materials remove a certain portion of the particulate, or liquid-solid phase of tobacco smoke, such as boiling tar and nicotine particles, these materials are of little value in removing the constituents in the gaseous phase of the smoke.
Although some of the gaseous constituents of tobacco smoke are desirable from the standpoint of taste, flavor and aroma, others, such as for example, aldehydes, phenols, and gas phase cyanide are undesirable and are quite irritating to the smoker's throat and lungs. In order to remove such vapors from tobacco smoke, various adsorbents or absorbents have been suggested in prior filters. Thus, materials such as silica gel, activated aluminum oxide, charcoal, and diatomaceous earths have been used. However, such products have many undesirable features, such as for example, the adsorption of moisture, odors, and the like. Also, said materials are not effective in the selective removal of the potentially harmful constituents of smoke, such as cyanides, phenols, aldehydes, and amines.
The isolation and identification of toxic substances in tobacco smoke is an essential part of deriving a relationship between smoking and health. A number of in vitro assay systems have been utilised to evaluate the toxicity of smoke. It is well recognised that tobacco smoke contains ciliotoxic substances capable of stopping the beating of cilia in the trachea. Ciliostasis is generally regarded as an index of cytotoxicity and can bring about a failure of the lung clearance mechanism. Hence the ciliostatic activity of smoke is considered by many workers as a measure of toxicity. Recently it has been shown that tobacco smoke contains a volatile factor which inhibits the activity of mammalian cytochrome oxidase. This inhibition of the ATP-generating system may contribute to some of the toxic effects of tobacco smoke.
Accordingly, an object of the present invention is to provide a tobacco smoke filter material that can be readily incorporated into filters for cigarettes, cigars and/or pipes.
Another object of the present invention is to provide an improved tobacco smoke filter which is effective in selectively removing potentially harmful constituents, such as for example, cyanides, phenols, aldehydes, and smoke, from a tobacco smoke stream.
A further object of the present invention is to provide a tobacco smoke filter material which contains a reactive chemical function chemically incorporated therein, said chemical function being capable of reacting with nucleophiles in tobacco smoke without losing its active component due to volatilization.
A still further object of the present invention is to provide a tobacco smoke filter which will remain effective for the removal of the potentially harmful constituents of smoke, such as cyanides, phenols, aldehydes, and amines, even after prolonged exposure to moisture vapor or tobacco odors as are normally encountered in a sealed package of cigarettes. Yet another object of the present invention is to provide a polystyrene-based resin with chemically active functions for use in isolating tobacco smoke fractions which exhibit toxicity.
According to the present invention, the preparation of the tobacco smoke filter material of the present invention is based upon the introduction of particular reactive chemical functions to an otherwise inert polymeric support material. Thus, the tobacco smoke filter material of the present invention comprises an imidazole-containing polymeric support material, said imidazole group being chemically bound to said polymeric support material. Although many polymers can be utilized to meet the requirements of the polymeric support material, polystyrene was found to be particularly effective as the polymeric support material utilized in the present invention. Thus, polystyrene will be referred to hereinafter as being exemplary of the support polymers which can be utilized in the present invention.
The synthesis of the chemically active resin can be achieved in three stages, that is, (A) the preparation of the polymeric support material, for example, polystyrene, (B) the introduction of carboxylic acids into the phenyl groups of the polystyrene, and (C) the conversion of the acid functions into active acyl imidazole groups.